to play the generic-brand-lego version of battleship.
You get to choose which ship of yours fires, and you have to tell your opponent which ship it is. You get as many shots as are "undamaged" on that ship, i.e. to start the game, you'd start with your aircraft carrier, because it gives you five shots (it takes 5 shots to sink it). If it sustains one hit, you only get 4 shots, or, you choose to shoot with whichever of the other 4-peg boats haven't been hit.
This actually makes the game go a lot quicker, but I think it's more fun because you can pay more round in the same amount of time.